Face de-identification methods have been proposed to preserve users' privacy
by obscuring their faces. These methods, however, can degrade the quality of
photos, and they usually do not preserve the utility of faces, i.e., their age,
gender, pose, and facial expression. Recently, GANs, such as StyleGAN, have
been proposed, which generate realistic, high-quality imaginary faces. In this
paper, we investigate the use of StyleGAN in generating de-identified faces
through style mixing. We examined this de-identification method for preserving
utility and privacy by implementing several face detection, verification, and
identification attacks and conducting a user study. The results from our
extensive experiments, human evaluation, and comparison with two
state-of-the-art methods, i.e., CIAGAN and DeepPrivacy, show that StyleGAN
performs on par or better than these methods, preserving users' privacy and
images' utility. In particular, the results of the machine learning-based
experiments show that StyleGAN0-4 preserves utility better than CIAGAN and
DeepPrivacy while preserving privacy at the same level. StyleGAN0-3 preserves
utility at the same level while providing more privacy. In this paper, for the
first time, we also performed a carefully designed user study to examine both
privacy and utility-preserving properties of StyleGAN0-3, 0-4, and 0-5, as well
as CIAGAN and DeepPrivacy from the human observers' perspectives. Our
statistical tests showed that participants tend to verify and identify
StyleGAN0-5 images more easily than DeepPrivacy images. All the methods but
StyleGAN0-5 had significantly lower identification rates than CIAGAN. Regarding
utility, as expected, StyleGAN0-5 performed significantly better in preserving
some attributes. Among all methods, on average, participants believe gender has
been preserved the most while naturalness has been preserved the least.